1. Field of the Invention
The present invention relates to systems and processes that provide for multiple imaging upon a television display and particularly to a system for distribution and presentation of alpha numeric and symbolic information on a multiple channel television system or systems.
2. Background
Cable television and other closed circuit television distribution systems presently distribute from one to over one hundred video signals. These signals originate from various sources, are not necessarily in synchronization with each other and are received and redistributed on the same channel or on different channels. This invention provides a method using one character generator circuit whereby alpha numeric or symbolic messages can be economically distributed to all individual television channels. This distribution may be a single message to a single channel, multiple messages to a single channel, multiple messages to multiple channels or a single message to multiple channels. The benefits of the ability to direct messages to channels in this fashion is illustrated in the following uses: a single message can be displayed on a single channel to notify subscribers that a program has been preempted or blacked-out; multiple messages to a single channel or multiple channels can be used to convey information; and a single message to multiple channels is ideal for use as an emergency message display system.
Cable television has for some time needed an emergency alert which could place messages onto programming on individual channels of a multiple channel system as a public service. Emergency alert systems as are presently available are audio based whereby an audio alert is introduced across all channels and the video signal turned off, or whereby a video message is caused to replace the video signal normally feed to that specific channel or all channels of a cable system. Constant reference is herein made to cable systems, though it should be understood, the same reasoning and explanation apply to an system which distributes multiple channels of video information. Some examples of other such systems would be hotels, businesses, colleges, or any community with closed circuit cable systems. These audio and full screen video replacements function properly as designed, but are seldom used because they totally disrupt operation of all channels of the system. This means the systems tend to be used only when the emergency actually exists such as a tornado has hit town or wind gusts are doing significant damage to a large area. The invention being considered provides the ability to prepare a community for an emergency in that it can display messages on all channels of a cable system without totally interrupting that system and it will therefore be used because it can notify without total disruption of basic operation.
3. Prior Art
The specific area toward which the present patent application is aimed defines a system of video character generation (alpha numeric display on a television screen) which is applicable to, but not limited to, emergency alert, blackout, promo, and timed messages.
The present invention utilizes a single character generator, which transfers pixel data to all channel modules, and the channel modules simply display that pixel data. Pixel data is individually synchronized into the program video of the video source or channel over which it is to be shown by the channel modules.
Devices for displaying a message over an existing video signal are common in television broadcasting. Such character generators, however, are limited to single channel operation rather than having economical multi-channel capability as does the present invention and are accordingly prohibitively expensive for use by a cable television company rebroadcasting a number of channels who must integrate a message on each or a number of the channels it rebroadcasts.
As set out above, heretofore, a message or messages into the video programs carried by one or a number of channels, unlike the present invention, has required a character generator for each channel. Further, where a multi-channel character display has been provided, for example, a patent to Dalke, et al., U.S. Pat. No. 3,909,818, shows such a system that provides for sorting input information and sending it for processing to a number of character generators and requires one character generator for every channel to be served. Whereas, the present invention provides for a multi-channel capability using a single character generator that is for location at the broadcast or rebroadcast source.
Like the Dalke, et al. patent, a number of message or information display systems have been developed for inclusion with a television receiver for providing a display that is integrated into a video display on a single channel at a time. Examples of a number of such systems are shown in patents as set out below, for example, a patent to Kimura, U.S. Pat. No. 3,891,792, involves a shift register and character generator that provides a message that crawls across the television screen. Burson, U.S. Pat. No. 4,180,805, is concerned with graphic color and provides an internal counter for generating horizontal and vertical drive pulses, rather than, as does the present invention, utilizing the horizontal and vertical drive pulses as exist in the received video for timing. A patent to Gastinel, U.S. Pat. No. 4,328,557, in addition to applying to a television set, does not address multiple channels, and is further unlike the present invention in that it is directed to a digital processor and cursor position indicator associated therewith. A patent to d'Hantecourt, et al., U.S. Pat. No. 4,338,624, is essentially a digital processor for connection to a conventional television and provides for modulating interface circuits for display of characters in specific colors. At patent to Ensigner, U.S. Pat. No. 4,374,399, is involved with a data encoder and method for data transfer rather than a data display that the present invention is directed to. A patent to Long, et al., U.S. Pat. No. 4,398,190, is concerned with a single CRT display rather than data transmission. A patent to Puskas, U.S. Pat. No. 4,419,662, deals with a multi-function character generator for a conventional television receiver. Horwood, et al., U.S. Pat. No. 4,435,729, is directed to a television receiver that includes a character generator. A patent to Van Vliet, et al., U.S. Pat. No. 4,441,105, provides a character generator for a television monitor that is addressed by external devices. Patents to Stell, U.S. Pat. No. 4,498,098, and to Bowker, et al., U.S. Pat. No. 4,599,611, each provide systems for closely timing a video switch to a video source for locking a computer generated graphics picture to a video signal at a television receiver. Willis, U.S. Pat. No. 4,595,953, shows a television receiver that includes a character generator with time lock and burst lock synchronizing arrangements, and patents to Skerlos, et al., U.S. Pat. No. 4,633,297, and Kinghorn, et al., U.S. Pat. No. 4,698,677, showing television receivers with micro processors. A patent to Priestly, U.S. Pat. No. 4,626,837, teaches a display interface for a television receiver that, like the present invention, utilizes vertical and horizontal drive pulses to generate access address data, but lacks a multi-channel and dot matrix type display capabilities of the present invention. Somewhat like the present invention a patent to Wine, U.S. Pat. No. 4,631,585, shows a utilization of vertical drive pulses for reset, it does not: utilize horizontal drive pulsing for signal access; is for use with a television receiver; and lacks the different input multi-channel capabilities and dot matrix type display of the present invention.
Summarizing, the present invention is directed towards cable companies who presently have or will have as a result of, FCC Syndex (Syndicate exclusivity) regulations, a requirement to switch off the video sources, which have been purchased in another market whose rebroadcast would violate exclusivity. Where, as set out above, a single channel message input at a broadcast source has been known and in common use such systems have been expensive. Accordingly, a cable company would be or will be required to have a single character generator for each channel to inform subscribers of the switch in programming as required by FCC regulations, the cost of which compliance will be prohibitively expensive.
Additionally, unlike the complex clocking arrangements of the cited patents, the present invention provides a simple switching arrangement that is operated by the horizontal and vertical drive pulses found in the video signal. In the present invention the input message information replaces a portion of the video signal as determined by a setting of a horizontal drive pulse counter, and switches back to the video signal at another setting of the horizontal drive pulse counter. The vertical drive pulse is used to reset the horizontal pulse counter. So arranged, the message input can conveniently replace the entire video signal or a portion thereof. While, of course, a number of systems like those set out above have involved a translation to digital, all have provided for conversion back to characters from the digital format for display. The present invention provides for a conversion of digital ASCII or other data format from the character generation to pixel for direct display as dots and vacant areas for forming characters on a video receiver screen much like a dot matrix printer. This means one character generator circuit can be used to create pixel data for numerous video displays.